The present invention relates to the use of an enzyme in bread making as bread improving activity.
A bread improving activity is one which improves any property of the baked product (particularly the bread volume and/or crumb structure of the bread), and/or improves any property of the dough. Throughout this specification the term bread volume should be read as xe2x80x98baked product volumexe2x80x99 where the content is appropriate.
A bread improving composition is added to a dough in addition to the basic ingredients which are generally flour, water, yeast and salt.
One of the most important characteristics of bread which is influenced by enzymes is bread volume. In order to obtain high bread volumes, compositions containing hemicellulase and/or amylolytic enzymes can be added. Hemicellulases are defined as enzymes capable of hydrolysing the non-starch polysaccharides in the flour. The commercially available compositions mostly originate from fungae, such as Aspergillus or Trichoderma. These compositions are unpurified mixtures of different enzyme activities. So far endo-xylanases and arabinofuranosidases have been identified as contributing to the activities of the bread improving compositions.
The use of hemicellulase preparations in breadmaking gives an improved oven spring, improved bread volume and an improved grain structure to the finished baked product. However, when hemicellulase preparations are used at higher concentrations the dough may become slack and sticky. This limits the use of hemicellulase preparations. Although the problem can be overcome by the addition of glucose oxidase, the need to add ad extra enzyme is a drawback. A better situation would be the availability of an enzyme with bread improving activity which has no negative side effects on the dough. This raises the possibility that emulsifiers may be replaced completely by enzymes. The resistance of consumers to chemical additives is growing and there is therefore a constant need to replace emulsifiers by consumer friendly additives such as enzymes.
The present invention provides the use of a CelloBioHydrolase (CBH), with bread improving activity to make bread. The CelloBioHydrolase is preferably CBH-I. The most important effects are an improved breadvolume and an improved crumb structure which are not accompanied by bad dough handling properties due to stickiness of the dough. Preferably the CBH is of microbial origin, more preferably fungal CBH is used. For example CBH can be obtained from Trichoderma or Aspergillus. CBH-I can be obtained from T. reesei, T. longibrachiatum and T. viride. Cellobiohydrolase I and II from Trichoderma reesei have been described in EP-B 0 137 280 and U.S. Pat. No. 4,894,338, respectively. CBH I has also been identified in Agaricus bisporus, Phanerochaete chrysosporium, Trichoderma viride and Humicola grisea. The present invention also discloses a composition with bread improving activity, which comprises CBH in an effective amount when added to other basic dough ingredients. The composition may also comprise effective amounts of xcex1-amylase and/or endo-xylanase.
By xe2x80x9ceffective amountxe2x80x9d is meant an amount of enzyme which is sufficient for providing a measurable effect on the intended effect, in case of CBH this would be a measurable effect of the improved breadvolume or improved crumb structure.
The fact that CBH has an effect in baking is surprising because CBH acts on cellulose which only constitutes 0.3% of wheat flour. CBH hydrolyses the 1,4-xcex2-D-glucosidic linkages in cellulose causing release of cellobiose. A possible explanation would be that CBH acts on cellulose-xylan interfaces in the endosperm cell walls.
As mentioned above the use of commercial preparation of the endo-xylanases of Trichoderma and Aspergillus is already known. Although traces of CBH are present in such preparations the amount of CBH is insufficient to contribute to improving the dough or bread. According to the present invention CBH can be used alone or in combination with other enzymes with bread improving activity, preferably endo-xylanase. Endo-xylanase can be obtained from Aspergillus or Trichoderma. Generally, use of the composition of the invention will give a dough with good handling properties, while the final baked product will have an improved volume and crumb structure.
With the use of CBH a controlled optimization of the bread improvers, or bread improving compositions, is possible.
It will be appreciated that the skilled person will be able to find the optimal amounts which can be added to the dough.
A composition of the invention can be used in combination with the normal bread improving constituents and enzymes, for example xylanases, xcex1-amylase, endo-xylanase, arabinofuranosidase, xcex2-amylase, glucoseoxidase, protease or lipase. The CBH can therefore be incorporated in a breadimproving composition. By xe2x80x98breadimproving compositionxe2x80x99 is meant a composition which comprises substances other than those conventially used in baking (i.e. flour, water, yeast, optionally salt), and which can be used to improve the properties of dough and/or the baked product.
The CBH may also be incorporated in a pre-mix. By pre-mix is to be understood a mixture of baking agents, in general including flour, which is prepared to ease handling in dough preparations processes. Normally a pre-mix will not contain the water necessary to prepare the dough.
The dough of the invention contains at least 0.5 mg of CBH per kg of flour, preferably 1 mg/kg of flour, more preferably more than 5 mg of CBH per kg of flour, even more preferable more than 10 mg of CBH per kg of flour. In general the amount of CBH is less than 100 mg of CBH per kg of flour, preferably less than 50 mg of CBH per kg of flour.